Driving of a peltier element as a cooling/heating element is normally controlled by turning on/off a direct-current power source. However, when controlling the driving by turning on/off the direct-current power source, a current flows to the peltier element at once, so that a temperature of the peltier element abruptly changes and a temperature stress is imposed on element components. A temperature difference between one surface (cooling surface) and the other surface (heat release surface) of the peltier element becomes, for example, 50° C. or higher, therefore, a temperature stress due to an abrupt temperature change easily causes a deterioration of the element, so that there has been a disadvantage that a lifetime of the peltier element becomes short.
To elongate the lifetime of the peltier element, it is considered to flow a current having an analog mild gradient by using a variable power source, however, such a variable power source device is expensive and disadvantageous in terms of costs.
A peltier element comprises a P-type thermoelectric element and an N-type thermoelectric element. The thermoelectric elements are electrically connected in series and sandwiched between a pair of substrates, so that a peltier module is formed. Such a peltier module is, for example, attached to a pusher provided in a handler of an electronic device testing apparatus for testing an IC device, etc. and used for controlling the IC device to be tested to be a desired temperature via the pusher.
In that case, a generally used structure is that the peltier module is bonded by pressure to an upper surface of the pusher via silicone grease, etc., a heat sink, etc. is bonded by pressure on an upper surface of the peltier module via silicone grease, etc. and the heat sink, etc. is fixed to the pusher by using a separate member.